Loss of power to furnace. Is this fix legit?

Old 01-08-20, 03:19 PM
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Loss of power to furnace. Is this fix legit?

Furnace has lost power. Power to "dedicated" breaker, but tracing this line messy to me.
the breaker is a double pole? (2 slots in panel used, and breakers are linked). Top one says spare, bottom says furnace.
starting at furnace going backward...

Red and white leave furnace to on/off switch on outside of furnace.
Red and white leave switch to GFI outlet on back of furnace.
GFI is for condensation pump, and GFI is pigtailed to connected furnace wires, and supply wires.
Following on... Next stop = one of those ceramic single bulb light fixtures with the pull chain for on, and off.

Next stop = a double junction box. In here the red goes to a yellow (with a black), and the white goes to a different yellow, and black.. then those 2 separate runs of wire go where I cant follow. Part of.this house is still knob and tube. At this point I am out of my knowledge base, so....my plan.

Add a new breaker at box, that is actually dedicated to furnace, except to add condensation pump outlet.

Then remove the existing furnace supply lines between light and furnace. Mark current breaker unknown,. and leave it off. Mark new breaker as furnace.

Thank you

Last edited by PJmax; 01-08-20 at 05:58 PM.
Old 01-08-20, 03:52 PM
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Sounds reasonable except what will power the light?
Old 01-08-20, 06:05 PM
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Welcome to the forums.

Red and white ??
Yellow and black ??
Is this wiring in conduit ?
If the wiring is in conduit..... trace it out.

You said circuit sounds messy but bringing a new feed over isn't going to help. You need to sort out what you have there. The light should not be attached to the furnace.
Old 01-08-20, 08:40 PM
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It's unlikely that a wire/cable went bad. It's possible it's a splice somewhere, but there really shouldn't be many splices between the panel and the furnace.

Do you have a voltage tester? (two leads and a neon bulb)
If so, I would start at the GFI receptacle and confirm if there's power going into the receptacle? Then see if there's any outbound at the breaker. Again - possibly check the connections at the splice box, but unlikely to be an issue.

It's also unlikely for the furnace to still be knob and tube. It was most likely upgraded to somewhat recent wiring when it was replaced a while back.

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